Overview of Crime Scene Investigation
Much of the physical evidence that is ultimately utilized in court is taken from the scene of the crime. While this information can be invaluable in ascertaining the truth in a criminal case, certain procedures must be followed in order to ensure the utility and integrity of this evidence. The validity of forensic evidence is only as good as the manner in which it was (1) collected, (2) preserved and transported, and (3) analyzed. It is critical that when crime scene evidence is presented, a defender investigate and challenge the way the evidence was obtained and tested.
Following is a basic overview of crime scene investigation. Defense lawyers should examine a crime scene investigation with an eye towards what evidence was discovered but also what evidence was not discovered or what steps did the investigators fail to take that they could have taken to gather more evidence at the scene of the crime.
Basic Stages in a Search (Overview)
- Approach Scene - Secure and Protect Scene
- Begin Survey/Determine Scene Boundaries
- Evaluate Physical Evidence Possibilities
- Prepare Narrative Description
- Take Photographs
- Prepare Diagram/Sketch of Scene
- Conduct Detailed Search
- Record and Collect Physical Evidence
- Conduct Final Review
- Release Crime Scene
- Be Alert for Discarded Evidence
- Make Notes as to Possible Approach/Escape Routes
Secure and Protect Scene
Securing the crime scene is essential to protect any evidence that it may contain, for the more people that visit the crime scene, the more difficult it becomes for investigators. Not only does securing the scene preserve important evidence, but it also helps in the identification of potential suspects/witnesses by eliminating the possibility of these people leaving/entering before investigators have the scene fully detailed. Investigators should do the following:
- Take Control of Scene on Arrival
- Determine Extent to Which Scene Has Thus far Been Protected
- Ensure Adequate Scene Security
- Take Extensive Notes - Do Not Rely on Memory.
- Keep Out Unauthorized People - Begin Recording who Enters and Leaves.
Start Preliminary Survey
- The Survey is an Organizational Stage to Plan for the Entire Search
- A Cautious Walk-Through of the Scene Should be Done
- Recognize Special Problem Areas
- Determine People and Equipment Needs - Make Specific Assignments.
- Identify and Protect Unstable Physical Evidence.
- Make Extensive Notes to Document Scene Physical and Environmental Conditions, Assignments of all Personnel on the Scene, Movement of People, etc.
- On Vehicles get License Number, Position of Key, Amount of Fuel in Tank, Lighting, etc.
Evaluate Physical Evidence Possibilities
- Based Upon What is Known from the Preliminary Survey, Determine what Evidence is Likely to be Present at the Scene – Specifically Investigate These Types of Evidence
- Focus First on the Easily Accessible Areas of the Scene in Open View and Progress to Possible Out-of-View Locations - Look for
Purposely Hidden Items
- Consider Whether the Evidence Appears to Have Been Moved Inadvertently
- Evaluate Whether or not the Scene and Evidence Appears Intentionally "Made-up"
Prepare Description and Document Scene
A well-documented scene ensures the integrity of the investigation and provides a permanent record for later evaluation by the prosecution, defense counsel and the court.
- The Purpose of this Step is to Provide a Running Narrative of the Conditions at the Crime Scene. Consider What Should be Present at a Scene (examples: dead body, victim's purse or vehicle) and What is not Observed and What is out of Place (example: ski mask)
- Consider Situational Factors: Lights on/off; Doors, Windows, open/closed; Smells; Ice, Liquids; Movable Furniture; Weather Conditions; Temperature; and Personal Items
- Consider Ways to Document Scene: Written, Audio, Video
- Begin Photography as Soon as Possible
- Document the Photographic Effort with a Detailed Log
- Make Sure That a Progression of Overall, Medium and Close-up Views of the Scene is Taken. Use Scale Devices (ruler, etc.) for ==Size Determination When Applicable
- Photograph Evidence in Place Before its Collection and Packaging
- Photograph Areas Adjacent to the Crime Scene - Points of Entry, Exits, Windows, Attics, etc.
- Photograph Items, Places, etc., to Corroborate the Statements of Witnesses, Victims, Suspects
- Take Photographs from Eye-Level to Represent Scene as Observed by Normal View
- Prior to Lifting Latent Fingerprints, Photographs Should be Taken
Prepare diagram/sketch of scene
- The Diagram Establishes Permanent Record of Items, Conditions, and Distance/Size Relationships - Diagrams Add to the Photographs
- Typical Material on Sketch:
- Specific location
- Case Number
- Weather conditions
- Lighting conditions
- Compass orientation
- Key or Legend to Show Larger Objects
- General Progression of Sketches:
- Lay out Basic Area
- Show Fixed Objects, Furniture, etc.
- Record Position of Evidence
- Record Appropriate Measurements
Conduct Detailed Search/Record, and Collect Physical Evidence
- Conduct Search in a General Manner and Work to the Specifics Regarding Evidence Items
- Photograph all Items Before Collection and Enter Notations in Log
- Mark Evidence Locations on Diagram/Sketch
- Complete Evidence Log with Appropriate Notations for Each Item of Evidence
- Ensure Evidence or Container of Evidence is Identified by Investigator Collecting Evidence
- Seal all Evidence Containers at the Crime Scene